A standard atmosphere is exactly 101,325 pascals.
Atmospheres to mmHgs Converter — atm to mmHg
Convert Atmosphere (atm) to mmHg (mmHg) using the exact conversion factor (1 atmosphere = 759.9998917 mmhg). See the formula, worked examples, conversion table, and common uses.
Atmospheres to mmHgs converter
Converter
Pressure Converter
Convert pascals, bars, PSI, atmospheres, mercury columns, water columns, and engineering pressure units.
Context values
Some unit families need one extra value for a physically accurate result.
Millimeters of mercury at standard gravity.
Result = input x 101325 / 133.3223874.
Pressure uses the pascal as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Atmospheres to mmHgs
Atmosphere and mmHg both show up on pressure gauges — psi is standard on US tire and tool specifications, while bar is the everyday pressure unit across most of the rest of the world. Atmosphere is most often used for chemistry (standard conditions are often defined at 1 atm).
Formula
mmhgs = atmospheres × 759.999891726
This factor comes from each unit's defined relationship to the category's base unit: 1 atmosphere equals 101325 base units, and 1 mmhg equals 133.322387415 base units, so dividing one by the other gives the direct atmosphere-to-mmhg factor of 759.999891726.
Simple example
1 atm × 759.9998917 = 759.9998917 mmHg
1 atmosphere = 759.9998917 mmhgs.
Real-world example
35 atm × 759.9998917 = 26,599.99621 mmHg
35 atmospheres = 26,599.99621 mmhgs.
Conversion table
| Atmosphere (atm) | mmHg (mmHg) |
|---|---|
| 1 atm | 759.9998917 mmHg |
| 5 atm | 3,799.999459 mmHg |
| 10 atm | 7,599.998917 mmHg |
| 25 atm | 18,999.99729 mmHg |
| 50 atm | 37,999.99459 mmHg |
| 100 atm | 75,999.98917 mmHg |
Reverse conversion: mmHg to Atmosphere
759.9998917 mmHg × 0.001315789661 = 1 atm
759.9998917 mmhgs = 1 atmospheres.
atmospheres = mmhgs × 0.00131578966114
For a page dedicated to this direction, see mmHg to Atmosphere.
Understanding the Atmosphere
Atmosphere (atm) measures pressure. Defined as exactly 101,325 pascals, originally based on the average atmospheric pressure at mean sea level. It is classified as a non-SI unit accepted for use with the SI.
Where it's used: Widely used internationally in chemistry, meteorology, and diving/aviation contexts alongside the pascal and bar
Uses of the Atmosphere today
- Chemistry (standard conditions are often defined at 1 atm)
- Diving and aviation pressure references
- General reference for everyday atmospheric pressure
Understanding the mmHg (mmHg)
Millimeters of mercury at standard gravity.
Atmosphere — sources
- BIPM SI Brochure — Standard atmosphere listed among non-SI units with a fixed exact value in pascals.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many mmhgs are in 1 atmosphere?
1 atmosphere equals 759.9998917 mmhgs, using the exact defined conversion factor rather than an estimate.
How do I convert atmosphere to mmhg?
Multiply the atmosphere value by 759.9998917. The converter above does this instantly to whatever precision you set.
How do I convert mmhg back to atmosphere?
Use the reverse factor: 1 mmhg equals 0.0013157897 atmospheres. You can also use the swap control in the converter above to flip the direction instantly.
What is a atmosphere?
Atmosphere (atm) measures pressure. Defined as exactly 101,325 pascals, originally based on the average atmospheric pressure at mean sea level. It is classified as a non-SI unit accepted for use with the SI.
What is a mmhg?
mmHg (mmHg) is a unit of pressure.
Is the atmosphere to mmhg conversion exact?
Yes. Defined as exactly 101,325 pascals, originally based on the average atmospheric pressure at mean sea level. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the atmosphere still used today?
Widely used internationally in chemistry, meteorology, and diving/aviation contexts alongside the pascal and bar